The lock burglars picked to break into the Democratic National Committees headquarters at the Watergate Complex in 1972.

WASHINGTON(AFP).- The lock of a door forced open in 1972, setting off the Watergate political scandal that transfixed the nation and eventually brought down a sitting US president, has been sold at auction for $62,500.

"The discovery of this tampered lock and the subsequent arrest of the five burglars set off a chain of events that would eventually lead to the resignation of President Richard Nixon," said the Nate Sanders auction house in its announcement of the sale late Thursday.

The humble lock was for the door to the Democratic Party headquarters in Washington's famed Watergate building complex.

The brass mechanism weighing about four pounds (1.8 kilograms) has been preserved for nearly half a century by the building's caretaker after a locksmith replaced it following the break-in.

The lock, mounted on a wooden panel, was sold with two letters certifying its authenticity.

The break-in at the Democratic Party office took place in the early hours of June 17, 1972. A sprawling investigation by two Washington Post reporters, Carl Bernstein and Bob Woodward, revealed a plot to bug the party's Watergate headquarters and the Nixon administration's attempts to cover it up.

Nixon was forced to leave his White House perch in August 1974 over the scandal, the only US president in history to resign.